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US Monitoring Database Reaches Limit, Quits Tracking Felons and Parolees
An anonymous reader writes "Thousands of US sex offenders, prisoners on parole and other convicts were left unmonitored after an electronic tagging system shut down because of data overload. BI Incorporated, which runs the system, reached its data threshold — more than two billion records — on Tuesday. This left authorities across 49 states unaware of offenders' movement for about 12 hours."
As the astonished submitter asks, "2 billion records?"
"According to the U.S. Bureau of Justice Statistics (BJS): "In 2008, over 7.3 million people were on probation, in jail or prison, or on parole at year-end — 3.2% of all U.S. adult residents or 1 in every 31 adults."
This doesn't make me feel safe.
it just stopped once it hit that limit rather than failing over to a backup process.
"just over 2 billion" is almost certainly 2^31 (2 147 483 648), or the maximum number representable by a signed 32-bit integer. People usually think of "over 4 billion" (2^32) as the integer limit, but that's for unsigned integers only, which are rarely used, especially in databases. I'm willing to bet that they used an "int" as a primary key in one of their tables, and simply overflowed the maximum possible value.
This kind of bug has impacted lots of systems in the past. If it happens, there's no "fail over" that could possibly save the system. The replica would have the same data, and hence the same issue, and would have failed as well. The usual fix is to extend the key type to 64-bits or longer (e.g.: GUIDs), but for a 2 billion row table, that's going to take hours at best, probably days.
Most database systems do not provide a warning when the keys start to approach large values, so it's easy to miss.
Anyone remember when Slashdot hit 16,777,215 comments, and overflowed MEDIUMINT? The ALTER TABLE statement that fixed it took hours to run. I shudder to think how long it'll take to fix this, even with the problem diagnosed.
There's no failure quite as dissatisfying as a complete and total solution to the wrong problem.
Posting anonymously for obvious reasons.
I was on electronic monitoring for the US BOP (bureau of prisons) through BI incorporated for about 3 years. I had to pay my own monthly bill for monitoring services, which went to BI incorporated in Colorado somewhere.
How the system works is like this: Your federal probation officer comes to your house and installs a box that looks kind of like a cable TV box. It connects to your telephone line (you must have a land line phone to be on electronic monitoring) on one end and also plugs into power. The box is pretty heavy because it has some rechargeable batteries in it so it can operate for some time if the power goes out.
You get an ankle bracelet installed that is pretty permanent - rubber band with a steel core around your ankle, and a pager-like device attached to it. Now, the device is pretty simple. Whenever you go out of range (about 100-200 ft.) of the box, it dials one of BI's modems and reports that you left. Whenever you come back in range of the box, it dials out and reports that you arrived home. If you disconnect it from power, or the power goes out, it also dials in and reports the power outage (you are never supposed to unplug it, but sometimes power outages happen). When the power comes back on, it dials in and reports the power is back online. Even if you never leave your house at all that day, it still dials in once a day to report it's status.
The purpose of this EM (electronic monitoring) system is to allow people to be on home confinement and still leave the house to go to work, get groceries, etc, but not be out at all hours of the night committing crimes.
I can easily see how 2 billion records are in the database. There are not 2 billion criminals. These are just 2 billion date/timestamp entries saying prisoner #X left their house, prisoner #X returned, etc.
I found the entire 36 month or so experience pretty surreal. The most difficult thing was wearing baggy pants to hide the ankle bracelet at work. For obvious reasons I didn't want to advertise to the world that I was a federal prisoner. It also says a lot about a society and judicial system where there are so many prisoners that they need to outsource the imprisonment of non-violent offenders to a corporation. But who am I to complain? I'm just a felon who committed a victim-less drug crime.
Posting anonymously for obvious reasons.
I was on electronic monitoring for the US BOP (bureau of prisons) through BI incorporated for about 3 years. I had to pay my own monthly bill for monitoring services, which went to BI incorporated in Colorado somewhere.
How the system works is like this: Your federal probation officer comes to your house and installs a box that looks kind of like a cable TV box. It connects to your telephone line (you must have a land line phone to be on electronic monitoring) on one end and also plugs into power. The box is pretty heavy because it has some rechargeable batteries in it so it can operate for some time if the power goes out.
You get an ankle bracelet installed that is pretty permanent - rubber band with a steel core around your ankle, and a pager-like device attached to it. Now, the device is pretty simple. Whenever you go out of range (about 100-200 ft.) of the box, it dials one of BI's modems and reports that you left. Whenever you come back in range of the box, it dials out and reports that you arrived home. If you disconnect it from power, or the power goes out, it also dials in and reports the power outage (you are never supposed to unplug it, but sometimes power outages happen). When the power comes back on, it dials in and reports the power is back online. Even if you never leave your house at all that day, it still dials in once a day to report it's status.
The purpose of this EM (electronic monitoring) system is to allow people to be on home confinement and still leave the house to go to work, get groceries, etc, but not be out at all hours of the night committing crimes.
I can easily see how 2 billion records are in the database. There are not 2 billion criminals. These are just 2 billion date/timestamp entries saying prisoner #X left their house, prisoner #X returned, etc.
I found the entire 36 month or so experience pretty surreal. The most difficult thing was wearing baggy pants to hide the ankle bracelet at work. For obvious reasons I didn't want to advertise to the world that I was a federal prisoner. It also says a lot about a society and judicial system where there are so many prisoners that they need to outsource the imprisonment of non-violent offenders to a corporation. But who am I to complain? I'm just a felon who committed a victim-less drug crime.
Another thing to mention is that what you see on TV or in the movies is pretty false. These are not GPS enabled tracking devices that can pinpoint your location on a map so they can hunt you down anywhere in the country. These are dumb radio devices that only have a 100-200 ft. range and the box uses dial-up modem technology from the 90s. I wouldn't be surprised if they ran the entire monitoring center on a few old PC servers.
Not a, uh, user - but here's an interesting background article: http://www.theatlantic.com/magazine/archive/2010/09/prison-without-walls/8195/